Messages in this thread | | | Date | Tue, 07 Oct 2008 16:45:34 -0700 | From | "H. Peter Anvin" <> | Subject | Re: [RFC] CPUID usage for interaction between Hypervisors and Linux. |
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Jeremy Fitzhardinge wrote: >> >> The big difference here is that you could create a VM at runtime (by >> combining the existing interfaces) that did not exist before (or was >> not tested before). For example, a hypervisor could show hyper-v, >> osx-v (if any), linux-v, etc., and a guest could create a VM with >> hyper-v MMU, osx-v interrupt handling, Linux-v timer, etc. And such >> combinations/variations can grow exponentially. > > That would be crazy. >
Not necessarily, although the example above is extreme. Redundant interfaces is the norm in an evolving platform.
>> Or are you suggesting that multiple interfaces be _available_ to >> guests at runtime but the guest chooses one of them? > > Right, that's what I've been suggesting. I think hypervisors should > be able to offer multiple ABIs to guests, but a guest has to commit to > using one exclusively (ie, once they start to use one then the others > turn themselves off, kill the domain, etc).
Not inherently. Of course, there may be interfaces which are interently or by policy mutually exclusive, but a hypervisor should only export the interfaces it wants a guest to be able to use.
This is particularly so with CPUID, which is a *data export* interface, it doesn't perform any action.
-hpa
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